Electric discharge tube



Oct 1936. G. ZECHER 2,056,641

ELECTRIC DISCHARGE TUBE Filed Jan. 19, 1929 Patented Oct. 6, 1936 UNITEDSTATES PATENT OFFICE 2,056,641 ELECTRIC msomm'cu TUBE ApplicationJanuary 19, 1929, Serial No. 333,666 In the Netherlands March 24, 1928'1 Claims.

This invention relates to an electric discharge tube and particularly toan incandescent cathode electric discharge tube adapted to emit rays,preferably ultra-violet rays.

It is known to assist the ignition of such discharge tubes by providingone or more auxiliary electrodes.

During the operation of such discharge tubes the disadvantage may accruethat a part of the tube wall which is intended for the transmission ofthe rays, is covered by disintegrated cathode material. Thus thetransparency of the said part of the tube wall to rays is decreased andthe efliciency of the discharge tube is materially reduced.

According to the invention, in an incandescent cathode electricdischarge tube for the emission of rays, preferably of ultra-violetrays, the incandescent cathode and the part of the tube wall which isintended for the transmission of rays have arranged between them one ormore screens which serve at the same time as auxiliary electrodes.

Such a discharge tube may be so constructed as to have extending withinthe discharge space a tube which may contain the substance to beirradiated one or more screens being arranged between the end of thesaid tube and the incandescent cathode.

Preferably the incandescent cathode is surrounded by a cylindricalscreen.

The invention will be more clearly understood by reference to theaccompanying drawing, showing some electric discharge tubes adapted toirradiate substances with ultra-violet rays.

In Figure 1 the part of the tube wall which is intended for thetransmission of ultra-violet rays and which may be, for example, ofquartz, is designated by I. This quartz part i has sealed to it glassparts 2 and 3. The stem 3 has mounted on it an incandescent cathode 4and a screen 5 which are connected to the leading-out wires 6 and l or 8respectively. The screen 5 prevents the quartz wall I from being struckby particles disintegrated from the cathode and serve at the same timeas an auxiliary electrode. The anodes 9 and ID are arranged in the part3 of the tube.

Referring to Figure 2, the wall ll of the discharge tube which may be ofglass for example, has sealed to it a tube l2 which extends within thedischarge tube H and which is made of a material that is transparent toultra-violet rays, for example, of quartz. The tube l2 has sealed to ita side tube I3 and also a tube I I which is The discharge tube II hastwo lateral arms 15 which have arranged in them the anodes l8 that aretaken through the tube at i'l.

- The stem i8 01 the discharge tube has mounted on it an incandescentcathode l9 to which leading-out wires 20 and 2i are connected and hasmoreover fixed to it a cylindrical screen 22 which protects the end ofthe quartz tube i2 from material particles disintegrated from theincandescent cathode l9. The screen 22 is connected to the leading-outwire 23 and is thus enabled to serve at the same time as an auxiliaryelectrode.

The substance to be irradiated is admitted through the tube It, ascendsthrough the tube l2 and is discharged through the side tube l3. Duringthis circulation the substance may be irradiated with ultra-violet lightgenerated in the discharge space of the tube I.

The discharge tubes are filled with a suitable gaseous filling, forexample, with a mixture of argonand mercury vapour which during thedischarge gives ofl light rich in ultra-violet rays.

What I claim is:

. 1. An electric discharge device for the emission of ultra-violet lightrays, comprising an envelope providing a discharge space and containinga cathode adapted to be heated to incandescence, an anode, an auxiliary,starting electrode, and a gaseous filling, said auxiliary electrodeforming a screen located in the discharge path between said anode andcathode and being arranged between said cathode and the part of theenvelope wall through which the ultra-violet light rays are emitted.

2. An electric discharge device for the emission of light rays,comprising an envelope providing an enclosed discharge space, andcontaining a cathode adapted to be heated to incandescence, an anode, anauxiliary electrode and a gaseous filling, said envelope comprising are-entrant tube adapted to contain a substance to be irradiated, saidauxiliary electrode forming a screen and being arranged between saidcathode and-the end of said tube extending within the envelope.

3. A gas filled electricdischarge device for the emission ofultra-violet light rays wherein the cathode material is normallyvaporized by positive ion impact thereon and deposited as an opaquecoating on the envelope wall, comprising an envelope providing adischarge space and containing a cathode adapted to be heated toincandescence, an anode, an auxiliary, starting electrode, and a gaseousfilling, the said auxiliary electrode forming a screen for interceptingparticles from said cathode and being located in the discharge pathbetween said anode and cathode and being between said cathode and thepart of the envelope wall through which the ultra-violet rays areemitted.

4. An electric discharge device for the emission of light rayscomprising an envelope, a

filamentary cathode adapted to be heated to in-' candescence, an anode,and an auxiliary electrode and a gaseous filling, said envelope having areentrant part adapted to contain a substance to be irradiated extendingtherein, said auxiliary electrode forming a screen and being arranged Ibetween the said filamentary cathode and the end of said re-entrant partextending within the envelope.

5. As a unitary structure, an envelope having a re-entrant tubular partfor the passage of matexial to be irradiated, and containing a cathodetubular part of smaller diameter or said envelope thereby deilning areverse path for material to be irradiated, the said tubular part orsmaller diameter being formed of material permeable to ultra violetrays, said envelope providing a discharge space and containing a cathodeadapted to be heated to incandescence, an anode, an auxiliary electrodeand a gaseous filling, the said anode being mounted in a tubular portionof!- set with respect to and communicating with that end 01' thedischarge space remote from the said cathode, the said auxiliaryelectrode forming a screen and being arranged between said cathode andthe part of the wall of the tubular part of and the re-entrant part ofsaid envelope.

GUSTAV ZECHER.

